When riveting many structures, such as for example aircraft wing assemblies, it is customary to clamp two or more workpieces together into a more or less rigid clamping assembly and to then proceed with the riveting operation. One riveting method and apparatus which has been utilized by the industry for a number of years is shown in U.S. Pat. No. 3,557,442. This patent discloses the utilization of slug rivets to secure two workpieces together, the more or less stationary workpieces being initially clamped together. This patent teaches that the upper rivet-forming anvil is initially extended to a full-down locked position. Thus, in order to accomplish the method and apparatus of this invention, it is necessary to either initially position the workpieces with respect to the tooling, or alternatively to properly position the tooling with respect to the workpieces. In some situations, due the very large size of the workpieces, such as for example an entire wing panel, an apparatus is provided, such as that shown in U.S. Pat. No. 3,534,896, wherein the tooling can be positioned with respect to the workpiece. It is also known that workpieces can be positioned with respect to tooling. Thus, if the tooling includes a frame which is only movable in a horizontal position, typically the fully extended lower position of the upper anvil is always in the same horizontal plane. In this case, it is therefore necessary to properly position the workpieces with respect to the tooling before the clamping operation is commenced in order to provide satisfactory results with prior art method and apparatus of this type. Thus, it can be seen that when this form of apparatus is utilized the workpiece must be properly positioned prior to the commencement of each riveting operation. While this procedure will give satisfactory results in the finished product, it is time consuming.